Neuroanatomy Flashcards
What are the divisions of the NS?
what are the 2 main categories of cells in CNS?
glia and neurons
what is the function of satellite cells?
surround neuronal cell bodies
what is the function of schwann cells?
myelination in PNS
what is the function of ependymal cells?
line ventricles
what is the function of microglia? (x2)
- phagocytosis
- scar tissue formation
what is the function of oligodendrocytes?
myelination in CNS
what is the function of astrocytes? (x2)
- surround synapses &capillaries
- help in potassium buffering
what are the different types of cell in CNS?
are neurons excitable or non excitable?
excitable
are glia excitable or non-excitable cells?
non-excitable cells
how are neuron impulses carried out and in what direction?
impulses carried out as AP’s, which can travel only in one direction from cell body to synaptic terminal
what does a neuron look like?
describe the main features of a typical neuron (5)
- multiple dendrites, one axon
- nucleus –> loose chromatin, prominent nucleolus
- high metabolic rate
- cytoplasm in cell body is called perikaryon and in axon is called axoplasm
- long living and amitotic
if there is injury to the neuron, what might happen in the long term to it?
axon can grow back, but if there is injury to cell body, loss is irreversible
how is the myelin sheath formed in the PNS?
by schwann cells
how is the myelin sheath formed in the CNS?
by oligodendrocytes
what is the effect of the myelin sheath?
increases the conduction speed in axons by ‘saltatory conduction’
what is the myelin sheath exactly?
nothing but a cell membrane
describe the process of myelination of axons
- schwann cells wrap around myelinated axons and a mesoaxon is formed
- cytoplasm of schwann cell is extruded, leaving only cell membrane
what happens to the myelination of non-myelinated axons in PNS?
-non-myelinated axons in PNS still get wrapped by schwann cells but myelin sheath isn’t formed
What are the 3 main types of neurons?
- multipolar
- bipolar
- pseudounipolar
What kind of neurons make up multipolar neurons?
- motor neurons
- interneurons
what kind of neurons make up bipolar neurons?
special senses neurons:
- olfactory mucosa
- retinal nerve fibres
what kind of neurons make up psuedounipolar neurons?
all sensory neurons in PNS
what do they look like?
describe multipolar neurons
-type of neuron that possesses a single axon and many dendrites
describe bipolar neurons
-has 2 cytoplasmic extensions attached to cell body -one serves as the axon and the other as the dendrite
describe pseudounipolar neurons
-one axon that splits into 2 branches –> one that goes to periphery and other to spinal cord
In CNS:
-what is the collection of cell bodies + non-myelinated axons called?
- grey matter (if diffuse)
- nuclei (if localised)
In CNS:
-what does the collection of myelinated axons form?
white matter or tracts
what are tracts?
bundles of axons carrying information within the white matter
In PNS:
-what do myelinated axons form?
nerves
In PNS:
-what do cell bodies (grey matter) form?
ganglia
- Pseudounipolar neuron
- Ganglion
- Tracts- white matter
- Nucleus
